Map: Poston Butte High School

SAN TAN VALLEY, Ariz. -- An 18-year-old San Tan Valley high school student faces charges in a sexual assault case and Pinal County officials said there could be at least a dozen other victims.

On March 25, the Pinal County Sheriff's Office received a call alleging that Tyler Kost had sexually assaulted, sexually abused and molested five teenage girls in the San Tan Valley area, according to Sgt. Pat Ramirez. Kost is a student at Poston Butte High School.

Detectives began investigating and have identified a total of 13 alleged victims. Ramirez said the victims are high school students and one victim is 13 years old.

"The young female victims in this case were threatened, harassed, stalked and then either forcibly sexually abused or sexually assaulted by Tyler Kost," Sheriff Paul Babeu said.

"[The assaults took place] n their own bedrooms, in his bedroom, in the desert, at a community pool, and in parks," Babeu added.

Ramirez said one of the victims reported Kost threatened her, harassed her and told her to kill herself. She attempted to commit suicide and was hospitalized.

"While in the hospital she received a message from Kost, threatening that if she returned to school he would 'make her life a living hell,'" Ramirez said in a news release.

The victim never returned to school and moved out of state.

Another 17-year-old girl and her mother told 3TV, Kost physically and verbally abused her a couple years ago.

"It got to where I didn't want to go to school. I couldn't be near him," said the girl, who asked to remain anonymous.

"It was bad. I cried everyday she stayed home from school," her mother said.

Florence Unified School District officials say Kost has been out of school for the past couple weeks, and taking online classes at home.

Kost complained of bullying by his male classmates, when word of the investigation leaked and spread among the students.

Kost was arrested Monday and booked into the Pinal County Jail for two counts of sexual assault and two counts of sexual misconduct with a minor related to one of the cases.

The judge set Kost's bond at $10,000, which was quickly posted and he was released from custody.

Detectives are continuing their investigation on the other cases and additional charges are pending.

"This investigation is still in the early stages and 13 victims have been identified and I am sure this number will climb," Babeu said.

Anyone with any information about these cases is asked to contact PCSO detectives.